Vascular endothelial growth factor (VEGF) is a known regulator of angiogenesis and neovascularization, and has been shown to be a key mediator of neovascularization associated with tumors and intraocular disorders (Ferrara et al. Endocr. Rev. 18:4-25 (1997)). The VEGF mRNA is overexpressed in many human tumors, and the concentration of VEGF in eye fluids are highly correlated to the presence of active proliferation of blood vessels in patients with diabetic and other ischemia-related retinopathies (Berkman et al., J Clin Invest 91:153-159 (1993); Brown et al. Human Pathol. 26:86-91 (1995); Brown et al. Cancer Res. 53:4727-4735 (1993); Mattern et al. Brit. J. Cancer. 73:931-934 (1996); and Dvorak et al. Am J. Pathol. 146:1029-1039 (1995); Aiello et al. N. Engl. J. Med. 331:1480-1487 (1994)). In addition, recent studies have shown the presence of localized VEGF in choroidal neovascular membranes in patients affected by AMD (Lopez et al. Invest. Ophtalmo. Vis. Sci. 37:855-868 (1996)). Anti-VEGF neutralizing antibodies can be used to suppress the growth of a variety of human tumor cell lines in nude mice and also inhibit intraocular angiogenesis in models of ischemic retinal disorders (Kim et al. Nature 362:841-844 (1993); Warren et al. J. Clin. Invest 95:1789-1797 (1995); Borgstrom et al. Cancer Res. 56:4032-4039 (1996); and Melnyk et al. Cancer Res. 56:921-924 (1996)) (Adamis et al. Arch. Opthalmol. 114:66-71 (1996)).
A number of antibodies are approved for therapeutic use in humans and other mammals, including anti-VEGF antibodies. The concentration of therapeutic antibodies in liquid pharmaceutical formulations varies widely depending, for example, on the route of administration. There is often a need for a high concentration formulation of an antibody when small volumes are desired. For example, high concentration formulations may be desirable for intravitreal injection or subcutaneous administration.
However, formulations with high concentration of antibody may have short shelf lives, and the formulated antibodies may lose biological activity caused by chemical and physical instabilities during storage. Aggregation, deamidation and oxidation are known to be the most common causes of antibody degradation. In particular, aggregation can potentially lead to increased immune response in patients, leading to safety concerns. Thus it must be minimized or prevented.
Formation of particulates in biotherapeutic formulations is also a major quality concern, as particulates in the tens of microns to sub-millimeter and millimeter size range can generally be seen by the naked human eye (see Das, 2012, AAPS PharmSciTech, 13:732-746). Particulates in therapeutic ophthalmic preparations can cause damage to the eye. Therefore, there are regulatory standards to ensure sub-visible particulate matter content in ophthalmic formulations is within certain limits. For example, the U.S. Pharmacopeial Convention (USP) has set requirements for particulate matter in ophthalmic solutions, such as the maximum number of particles ≥10 μm diameter is 50 per mL, the maximum number of particles ≥25 μm diameter is 5 per mL, and the maximum number of particles ≥50 μm diameter is 2 per mL determined by the microscopic method particle count (see USP General Chapter <789>).
Methods for producing high concentration antibody formulations are known. However, a universal approach does not exist to overcome the unpredictable impact of an antibody's amino acid sequence on its tendency to form aggregates or degrade in the presence of various pharmaceutical excipients, buffers, etc. Further, preparing an ophthalmic formulation with a high concentration of protein (such as an antibody) that contains an acceptable level of sub-visible particles is challenging and not predictable.
It is an object of the invention to provide further and improved formulations with high concentration of anti-VEGF antibodies and low levels of antibody aggregation and sub-visible particles, that are suitable for administration to a human, in particular to a human eye.